When a patient is a candidate for stimulation therapy such as sacral nerve stimulation or spinal cord stimulation therapy to treat incontinence, chronic pain, or related conditions, it is often desirable to conduct a trial period of stimulation. This trial period allows an external stimulator to be used so that the patient is not required to undergo a full stimulation device implantation procedure. If the trial is successful, then an implantable stimulator is fully implanted into the patient.
When implanting the trial system, an implantable medical lead is implanted with a distal end being routed to the stimulation site. An implantable lead extension is typically then routed subcutaneously from the location of the proximal end of the implanted medical lead to an exit site nearby the location where the external device will be mounted to the patient. In some cases, an external lead is then used to interconnect the exposed proximal end of the implantable lead extension to the external device. In other cases, the exposed proximal end of the implantable lead extension is connected directly to the external device.
To route the implantable lead extension, a subcutaneous tunnel is first created between the exit site nearby the position of the external device and the location of the proximal end of the implanted lead. A physician uses a tunneling tool to create the tunnel. The physician then loads the proximal end of the lead extension into a carrier of the tunneling tool and retracts the tunneling tool back through the tunnel to thereby pull the lead extension through the tunnel. The tunneling tools for this approach may be adequate for lead extensions having proximal connectors that are relatively small, such as where an external lead will be used to connect the lead extension to the external device. However, the conventional tunneling tools that utilize this approach are impractical in other situations. For instance, conventional tunneling tools may not be effective where the lead extension has a relatively large proximal connector such as where the proximal connector connects directly to the external device.